Research Objective: Continuing study of the relationship of respiratory viruses to vitamin A deficiency in children of a village in western West Bengal, with viral isolates identified at the virus laboratory in Calcutta. An epidemiologic study of respiratory viral infections at higher altitudes has recently been started in Nepal, with emphasis on domestic animals as possible reservoirs of new infections in man. Continuing studies of the immune responses in various degrees of malnutrition, with measurement of cell-mediated immunity in children before and during refeeding, done in both Calcutta and Dacca. New study of the immune response during smallpox, with measurement of some parameters of cellular and humoral immunity, recently started in Dacca. Continuing study of rodent ecology in relation to energy sources with emphasis on the destruction of food-grains by bandicoot rats in Nepalese villages. New study in Nepal of aggressive behavior in rhesus monkey troops, following similar studies that have been carried out in India during recent years. New study on the dynamics of filariasis transmission, to be set up in Bangladesh under supervision of a medical entomology team. Continuing study of hematologic problems among Nepalese populations including distribution of thalassemia and various hemoglobin abnormalities. A similar study will likely be done in Bangladesh. Continuing studies on cholera and cholera-like diarrheas in Bangladesh, with ancillary studies on osmo-regulation of the canine intestine as affected by enterotoxin and mediator inhibitors. New studies on malabsorption syndromes will be implemented as feasible. Continuing studies on ecology and chemotherapy of schistosomiasis in Ibadan, Nigeria.